Stimulating hepatocytes with IL-1beta - (Apr/13/2010 )

I'm wondering if anyone knows of a generic concentration of IL-1beta that could be used in a stimulation experiment on hepatocytes? I am using Hep89 cells, and I want to stimulate in 6-well plates with estradiol-only and estradiol with IL-1beta. I wouldn't be sure on a concentration, no time to do a conc curve and papers only give values at 100U/ml which is no good to me as the protein I have is at 25ug/ml.
Any suggestions?